Firebase cohorts shows too high retention?

[wronek]

I googled the problem but found nothing. Two cohorts showing retention in Android app, first from Game Analytics and the second from Firebase, same period and dates:

We've also implemented other analytic SDKs for this app (Facebook and Unity) and they show similar retention to that from GA, not Firebase - Firebase's results are always way higher. It's hard to believe that 3 other analytics are wrong, but on the other hand Firebase can send events after user close it's app afaik and maybe that's the source of gap - but that gap is still too high IMO. After filtering out pirates from Firebase cohorts in BigQuery results are even higher. Has someone stumbled on this problem?